Hello @AdamD ,
you can't use any expression on the SP column when using in the OData query, you must use it as it is, all operations must be done on right side of the condition in the 'value' part.
To get everything older than one year I'd compare the DateColumn with today's date - 1 year:
DateColumn lt '@{addToTime(utcNow(),-1,'Year')}'
and add the IsActive filter, I guess it's a Yes/No column so you should compare it with 1/0 value:
Date lt '@{addToTime(utcNow(),-1,'Year')}' and IsActive eq 1